As is known in the art, an electronically scanned array (ESA) is a type of phased array antenna for use in radar systems wherein transmit and receive beams can be electronically formed and directed (or “pointed” or “steered” or “scanned”) by appropriate phasing of antenna elements. A passive electronically scanned array (PESA), also known as passive phased array, is a type of ESA in which the antenna elements are connected to a single transmitter and/or receiver. PESA radar systems may include a single RF signal generating source accompanied with a radiating aperture consisting of an array of elements that phase shift the RF signal to form beam shapes and steer the beams.
Existing ESAs are more expensive than a mechanically scanned antenna of comparable size and power. In addition, existing ESAs may have relatively large fixed-shaped apertures that cannot be easily collapsed for compact transportation and/or storage.